The present invention is related to a rolling bearing apparatus for supporting an axle of a railway vehicle.
One example of conventional bearing devices for rotatably supporting an axle of a railway vehicle is a rolling bearing apparatus including a double row tapered roller bearing provided at an end portion of the axle, and sealing devices provided respectively at axially-opposite ends of this double row tapered roller bearing. For example, JP-UM-5-22853 discloses such a bearing device.
FIG. 4 a cross-sectional view of a portion of a conventional rolling bearing apparatus used in a railway vehicle. This rolling bearing apparatus 100 comprises an inner ring 101 fitted on an axle S, an outer ring 102 fixed to the vehicle, tapered rollers 103 disposed between the inner and outer rings 101 and 102, and a sealing device 104 sealing a space between the inner and outer rings 101 and 102. The sealing device 104 comprises a seal case 105 fixed to the outer ring 102, and a seal member 106 retained by the seal case 105 and forming a seal between the seal case 105 and the axle S. The seal case 105 is fixed to an end portion of the outer ring 102, and includes a tubular fixing portion 105a press-fitted in an inner periphery of a shoulder portion 102a of the outer ring 102 to be fixed thereto, a ring-shaped portion 105d extending radially inwardly from an axially-outer end of the fixing portion 105a, and a tubular retaining portion 105b which extends axially outwardly from an inner peripheral edge of the ring-shaped portion 105d away from the outer ring 102 and retains the seal member 106 at a region disposed axially outwardly of the end face of the outer ring 102.
A ridge 105c is formed on and projects radially outwardly from a distal end portion of the fixing portion 105a. This ridge 105c is engaged in a seal groove 102b formed in the shoulder portion 102a, thereby limiting an axially-outward movement of the seal case 105.
In the above conventional rolling bearing apparatus, the sealing device 104 forms a seal between the seal case 105 and the axle S by the seal member 106, and also forms a seal between the seal case 105 and the outer ring 102 by surface-to-surface contact between the inner peripheral surface of the shoulder portion 102a of the outer ring 102 and the outer peripheral surface of the fixing portion 105a press-fitted in the inner peripheral surface of the fixing portion 105a. 
However, the radially outwardly-projecting ridge 105c is formed at the distal end portion of the fixing portion 105a, and therefore when press-fitting the fixing portion 105a into the outer ring 102, the fixing portion 105a is deformed radially inwardly by an amount corresponding to an amount of radially-inward displacement of the ridge 105c by the inner peripheral surface of the outer ring 10, and when this deformation exceeds the range of elasticity (that is, the fixing portion 105a is plastically deformed), a clearance is formed between the inner peripheral surface of the shoulder portion 102a of the outer ring 102 and the outer peripheral surface of the fixing portion 105a. 
Furthermore, when press-fitting the fixing portion 105a into the outer ring 102, the ridge 105c is often chipped upon contact with the inner peripheral surface of the shoulder portion 102a of the outer ring 102, and when a chip resulting from the ridge 105c is caught between the inner peripheral surface of the shoulder portion 102a of the outer ring 102 and the outer peripheral surface of the fixing portion 105a, there is a possibility that a clearance may be formed therebetween.
When a clearance is thus formed between the inner peripheral surface of the shoulder portion 102a of the outer ring 102 and the outer peripheral surface of the fixing portion 105a as described above, there are fears that dust, dirt, etc., may intrude into the interior of the rolling bearing apparatus and that grease within the bearing device may flow to the exterior, and as a result the durability of the rolling bearing apparatus is lowered. Therefore, it has been desired to provide means for forming a positive seal between the outer ring 102 and the seal case 105 so that the sealing performance of the sealing device can be enhanced.